Since 1973 the first primary lithium battery was commercialized by Sony. These electrochemical cells have been applied widely as the power supply in a variety of electronic devices for decades. The developing functions of these devices always need the batteries with higher energy density. On the other hand, to decrease the pollution and greenhouse gas emissions is becoming urgent nowadays and driving the demand of new batteries with better performance as well.
The lithium electrochemical cell consists of three fundamental components, anode, electrolyte and cathode. Lithium metal or Li contained alloy, graphite-like materials, metal oxide, sulphide, nitride, etc., that have low reduction potential can be used as active anode materials. Generally lithium salt dissolving in no aqueous system is used as electrolyte. Cathodes are the compounds that can take the lithium ions into the structure along with electrochemical reaction and meanwhile produce energy. The chemical potential and specific capacity of anode and cathode decide the energy density of the battery.
Manganese oxide (MnO2) has been used as active cathode material in dry-batteries for a long time. Until now it is still playing an important role in the commercial primary lithium batteries due to the good performance, sufficient resource and economic price. MnO2 has various kinds, including natural ore, e.g. pyrolusite, ramsdellite, nsutite (is called as NMD), prepared compound by chemical process (CMD) and by electrolytic process (EMD). EMD MnO2 is very common industrial used raw chemical that can be further treated and applied as the active cathode material in batteries. The crystal structure of EMD is called γ-MnO2, and it is treated with different temperature to form β-MnO2 phase or β-γ-MnO2 mixed phase, which can be optimized as promising cathode material in primary Li batteries. The other phases of cathode MnO2 include α-MnO2, δ-MnO2, ε-MnO2, and λ-MnO2. Amorphous, mixed phases, lithiated and modified phases can also be applied as active cathode materials in Li batteries. A lot of patents have contributed to the different produce processes that can improve the electrochemical performance of MnO2 related cathodes, such as U.S. Pat. Nos. 4,297,231, 5,698,176 and 6,403,257.
Vanadium oxides have been investigated as battery materials for decades due to its high oxidation state (5+) and capability to be reduced to lower oxidation state (4+, 3+), which is expected to produce high energy density. They may be used as active cathode in Li battery. A lot of efforts have been carried on in the studies of different types of vanadium oxides such as V2O5, LiV3O8, (Li1.3-yCuy)V3O8, VO2, V6O13 and Li3V6O13.
To use blended materials as active materials was proposed in several patents such as blended cathodes of Ag2CrO4 and Ag3PO4 (U.S. Pat. No. 3,981,748), lithium cobaltate and manganate spinel for secondary batteries (U.S. Pat. Nos. 7,811,707, 7,811,708). Mixtures of MnO2 and CFx can be also used as promising active cathode materials in primary lithium batteries (US 2009/0081545). In JP 2575993 and US 2007/0072081, V2O5 and LiV2O5 were used as one component of mixture cathode materials in secondary batteries. In US publication 2013/0216903, the synergetic effect of specific capacity in secondary batteries was found in blended LixHyV3O8 and LiFePO4, but not in the system of LixHyV3O8 and LiCoO2.
The drawbacks of the known electro-active materials for primary batteries are their lack of specific capacity and of energy density.
It is therefore necessary to propose a new electro-active material for primary batteries with higher specific capacity and energy density.
It is also necessary to propose a new electro-active material for primary batteries with high energy density which allows to be produced by an economic method and by using materials with sufficient resource.